1. Field of the Invention
The present invention relates to a feed or supply station in a metal wire shaping machine.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
A numerically controlled machine carries out various shaping operations on a metal wire (or on a bar), such as for example cambering, bending, etc. . . . , executed by various stations mounted on a frame.
The word metal wire is a generic term professionally used, which means a wire proper as well as a bar or a tube.
One of the stations is the wire feed station which horizontally supplies said wire along a travel axis, to the tools of a shaping station.
The wire is moved by the feed station using grooved rollers functioning in pairs and rotating in reverse directions with respect to each other, generally the rollers are positioned one above the other, with a stationary lower roller and an upper roller which can be moved vertically in one direction and the other.
The wire is clamped between said two rollers by these moving closer to one another and it is placed in the annular grooves of said rollers.
The movable roller is actuated by an actuator which defines the tightening stress on the wire and which can be a screw, a pneumatic or hydraulic jack, an eccentrics system or any other system.
The number of roller pairs varies as a function of the wire diameter and/or the shaping operations to be carried out thereon.
Two mountings of the rollers of the same pair of rollers are possible. First, a mounting wherein the shafts supporting the rollers are mounted in two bearings, with a rear bearing of at least one of the shafts which must be swivelling, which causes, when the rollers come closer to each other, a shears effect, through the misalignment of the peripheral annular grooves of the rollers between which the wire travels. Such defect tends to rotate the wire about the travel axis thereof, during the feeding of the wire and generates dispersions between the parts manufactured downstream on the shaping station. A mounting of this type is shown as an example in appended FIG. 1a, with a feed device wherein the shaft (a) of the upper roller (not shown) is mounted on a swivelling bearing, i.e. mounted on a spherical bearing (b) and actuated by a pneumatic actuator (c).
Second, a mounting wherein the shafts supporting the rollers are each mounted in a single bearing, and wherein the relative movement thereof requires guiding means such as, for example, columns, guiding blocks or any other one. In such a type of mounting, the slightest clearance in said guiding means (for example mounting clearance and/or wearing clearance) generates a misalignment of the rollers peripheral grooves and thus generates the same defects as with the previous mounting. A mounting of this type is shown, as an example, in FIGS. 2a and 2b, wherein the wire (d) is clamped between two pairs of rollers (e, f). Two rollers (e, f) of the same pair are mounted on a single bearing with two guiding bearings (g, h) in the same part, with the guiding means being a guiding column (i).
For both above-mentioned types of mounting, the number of parts required for guiding the shafts is significant, which implies a long chain of dimensions and a poor guiding final accuracy which is not satisfactory, considering the reproducibility of the parts to be shaped.
The aim of the invention consists in solving the problems of the feed devices of the prior art by limiting the number of parts as well as limiting the clearances which generate the shear effect.